Low cost, wide area RFID system

ABSTRACT

Techniques for radio-frequency identification systems include sensor systems having a sensor unit and one or more sensors and a server. The sensor system includes one or more antennas at a location configured to receive signals from a tag proximate to an antenna and a processor configured to process tag detection signals based on the received signals. The processing may include selectively storing tag detection signals received from one or more antennas and identify an event related to the presence of a tag proximate to an antenna at the location. Sensor system may include a transmitter configured to transmit a message indicating the event over a network to a server. The server may be configured to process the message by analyzing a feature of the signals related to the event. The analysis may evaluate an adjustment of a configuration parameter used to operate an antenna. The configuration parameter may be updated by the server, and the server may transmit a message indicating the configuration parameter to the sensor system.

BACKGROUND

Radio-frequency identification (RFID) technology may be used to identifyand/or track objects by attaching tags to the objects and placingsensors to detect the tags. A sensor with one or more antennas may readthe identification information stored on a tag. For example, a sensor orreader may read the identification information on a tag by transmittingan electromagnetic signal, which powers the tag through electromagneticinduction, allowing the tag to transmit a signal containing theidentification information. An antenna may receive the signal, and thesensor may report the detected tag to a user. RFID systems may be usedin a variety of applications where it is desirable to track objects suchas goods, people, and/or animals.

SUMMARY

According to an aspect of the present application, a system is provided.The system comprises a plurality of antennas deployed in a location.Each antenna of the plurality of antennas is configured to receive asignal indicative of a tag proximate to the antenna. The system furthercomprises a memory and a processor configured to process tag detectionsignals that are based on the received signals. The processing comprisesselectively storing tag detection signals in the memory and identifyingan event related to presence of a tag at the location based on aplurality of tag detection signals. The plurality of tag detectionsignals comprising at least one stored tag detection signal. The systemfurther comprises a transmitter configured to transmit a messageindicating the event over a wide area network to a server.

In some embodiments, identifying an event comprises identifying that atag detection signal of the plurality of tag detection signals includestag identification information that matches tag identificationinformation of the at least one stored tag detection signal. In someembodiments, the tag detection signal of the plurality of tag detectionsignals is based on signals received by a first antenna of the pluralityof antennas and the at least one stored tag detection signal is based onsignals received by a second antenna of the plurality of antennas.

In some embodiments, the processor is further configured to store timeinformation associated with the at least one stored tag detectionsignal, and identifying an event comprises comparing the timeinformation associated with the at least one stored tag detection signalto time information associated with at least one other tag detectionsignal of the plurality of tag detection signals. In some embodiments,an event is identified by comparing a difference between the timeinformation associated with the at least one other tag detection signaland the time information associated with the at least one stored tagdetection signal to a time interval. In some embodiments, an event isidentified when a difference between the time information associatedwith the tag detection signal of the plurality of tag detection signalsand the time information associated with the at least one stored tagdetection signal is greater than a time interval, and the tag detectionsignal of the plurality of tag detection signals includes tagidentification information that is distinct from the tag identificationinformation of the at least one stored tag detection signal. In someembodiments, an event is identified by an absence of at least one tagdetection signal corresponding to the tag for an amount of timeexceeding a time interval.

In some embodiments, the at least one stored tag detection signal ismodified to reflect the identified event. In some embodiments, the atleast one stored tag detection signal is deleted from the memory when adifference between time information associated with the at least onestored tag detection signal and a current time is greater than apredetermined time interval. In some embodiments, the transmitter isconfigured to transmit the message via at least one data buffer, and theat least one data buffer is configured to store at least a portion ofthe message when the transmitter is unable to transmit the message. Insome embodiments, the transmitter is configured to transmit at least aportion of the message over the wide area network when the system is incommunication with the server and the at least one data buffer isconfigured to store at least a portion of the message when transmissionof the message is interrupted.

According to an aspect of the present application a system is provided.The system comprises a wide area network receiver configured to receive,from a sensor unit having a plurality of antennas, a message reportingat least one event identified by the sensor unit processing signalsreceived from a tag proximate to an antenna of the plurality of antennasand at least one feature of the signals. The system further comprises aprocessor configured to process the message. The processing comprisesanalyzing the at least one event and the at least one feature toevaluate adjustment of a configuration parameter used to operate thesensor unit or at least one antenna of the plurality of antennas andupdating the configuration parameter when analysis of the at least oneevent and the at least one feature indicates adjusting the configurationparameter. The system further comprises a wide area network transmitterconfigured to transmit the updated configuration parameter to the sensorunit.

In some embodiments, processing the message further comprises analyzingthe at least one event to identify a portion of the at least one eventthat consolidates a number of occurrences for an event type. In someembodiments, processing the message further comprises analyzing the atleast one event and the at least one feature to identify informationindicative of a status of the sensor unit, and the processor is furtherconfigured to present a status message indicating the status to a user.In some embodiments, the updated configuration parameter is used tooperate the at least one antenna in response to the sensor unitreceiving the updated parameter. In some embodiments, processing themessage further comprises presenting information related to the messageto a user. The information presented to the user indicates a status ofthe sensor unit.

According to an aspect of the present application, at least onecomputer-readable medium storing computer-executable instructions that,when executed, perform a method is provided. The method comprisesreceiving, from a plurality of antennas deployed in a location, signalsindicating a tag proximate to an antenna of the plurality of antennas.The method further comprises processing, by a reader unit incommunication with the plurality of antennas, tag detection signals thatare based on the received signals. The processing comprises selectivelystoring tag detection signals and identifying events related to presenceof a tag at the location based on a plurality of tag detection signals,the plurality of tag detection signals comprising at least one storedtag detection, and wherein the events include a plurality of eventtypes. The method further comprises transmitting a message indicatingthe events from the reader unit over a wide area network to a server.

In some embodiments, the received signals indicate at least oneconfiguration parameter of the antenna, and identifying events is basedon the at least one configuration parameter. In some embodiments, theplurality of event types includes an event type corresponding to arrivalof the tag to a region proximate to an antenna of the plurality ofantennas at the location. In some embodiments, the plurality of eventtypes includes an event type corresponding to departure of the tag froma region proximate to an antenna of the plurality of antennas at thelocation. In some embodiments, the plurality of event types includes anevent type corresponding to movement of a user associated with the tagfrom a first region proximate to a first antenna at the location to asecond region proximate to a second antenna at the location.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is an exemplary RFID system for identifying events associatedwith objects having RFID tags.

FIG. 2 is a functional block diagram of an exemplary sensor system andserver as part of an RFID system.

FIG. 3 is a functional block diagram of an exemplary server configuredto receive messages from a sensor system.

FIG. 4 is a flowchart illustrating an exemplary method for identifyingprocessing tasks for event identification related to a tag detectionsignal.

FIG. 5 is a flowchart illustrating an exemplary method for processingtag detection signals received from antennas configured to operate inportal mode.

FIG. 6 is a flowchart illustrating an exemplary method for processingtag detection signals received from antennas configured to operate inPortal IN mode.

FIG. 7 is a flowchart illustrating an exemplary method for processingtag detection signals received from antennas configured to operate inPortal OUT mode.

FIG. 8 is a flowchart illustrating an exemplary method for processingtag detection signals received from antennas configured to operate inPresence mode.

FIG. 9 is a flowchart illustrating an exemplary method for processingtag detection signals received from antennas configured to operate inMuster mode.

FIG. 10 is an example of a suitable computing system environment inwhich embodiments of the invention may be implemented.

DETAILED DESCRIPTION

The inventors have recognized and appreciated techniques that enableoperation of a radio-frequency identification (RFID) system toeconomically generate large quantities of useful information. Such asystem may be implemented with relatively inexpensive hardware. As aresult, the RFID system may be deployed over a wide area and may becapable of tracking a large number of objects with RFID tags.

The data collected by the RFID system may be sent to one or more serversfor analysis. In some embodiments, the one or more servers may becloud-based servers, such that further efficiencies may be achieved byusing readily available and low cost networking and computationservices, without the need for any special hardware deployment. Sensors,for example, may be deployed in virtually any location in the worldwhere a connection to the Internet is possible. Yet, data from thesesensors may be analyzed alone or in conjunction with data from sensorsdeployed in any other location in the world.

To enable the use of existing networks and computation services, sensorunits may be deployed in connection with sensors. The sensor units mayperform one or more functions that facilitate wide scale deploymentusing existing networking and computation resources. Each sensor unit,for example, may process tag detection signals derived from the sensorsto identify events. Events, for example, may indicate that a tag hasentered or left a location in which the sensors are deployed or that atag is present or was present in a location for an amount of time longerthan a time interval. In some embodiments, sensor units may beconfigurable such that the type or types of events detected may be setfor the sensor unit.

In support of this process, the sensor unit may include a memory and maystore in the memory tag detection signals along with time stamps. Tagdetection signals may be selectively stored, based on the utility of atag detection signal in identifying an event of the type the sensor unitis programmed to recognize. Selective storing of the event signals mayreduce hardware requirements for each sensor unit. Identification of anevent related to presence of a tag at a location may be based on aplurality of tag detection signals including one or more tag detectionsignals stored in the memory of the sensor unit.

To facilitate operation over low cost networks with limited bandwidth,sensor units may also include memory that acts as a buffer for messagesindicating a detected event to be sent to a server. If networkconnectivity fails or events are temporarily detected at a rate fasterthan messages reporting those events can be transmitted over thenetwork, the messages may be buffered until network connectivity isrestored or there is available network bandwidth for a message.

Such an RFID system may be used for any of a number of purposes. SomeRFID systems are used to track one or more objects by tracking a tagattached to an object, where the tag contains electronically storedinformation that uniquely identifies the tag, and, by associating aspecific tag to an object, the RFID system can be used to track theobject. A tag detection signal may include tag identificationinformation that identifies a certain tag and/or object. Identificationof an event related to presence of a tag at a location may includecomparing tag identification information associated with the tag and tagidentification information for one or more stored tag detection signals.Stored tag detection signals with tag identification information thatmatches the tag identification information associated with the tag maybe used to identify previous locations of the tag. For example, an RFIDtag attached to the personnel's gear (e.g. helmet, badge) can be used touniquely identify, and therefore track, the wearer of the gear. In someembodiments, for example, tracking may be performed by a cloud server orother computer processor that receives event indications from multiplesensor units.

As part of an RFID system, one or more antennas as part of a sensorsystem can be arranged to detect an object associated with a tag bysending interrogation signals and receiving response signals when thetag is located proximate to an antenna. By processing tag detectionsignals collected at multiple antennas deployed in one location,movement of an object into, out of, or within that location may beidentified. By sending information about tags detected in multiplelocations to a server or other processor, movement of objects across awide area, including multiple locations, may be determined. Tagdetection signals based on signals received by a first antenna may becompared to stored tag detection signals based on signals received by asecond antenna. An event may be identified by comparing tagidentification information of the tag detection signal associated withthe first antenna and the stored tag detection signal associated withthe second antenna. The event may indicate that the tag moved from aregion proximate the second antenna to a region proximate the firstantenna.

At each location, interrogation signals from an antenna may power a tagthrough electromagnetic induction when the tag is in proximity to theantenna, allowing an RFID tag to transmit an authentication response. Bypositioning one or more antennas at certain areas of interest at alocation, information about a tagged object's movements and/or presenceof the tagged object with respect to those areas of the location can beobtained by analyzing the signals received by the one or more antennas.For example, antennas placed within a building, such as in a doorway,can be used to detect personnel with tags passing through the doorway.Detection of users may be used for a variety of purposes, includingsafety requirements and security precautions. Additionally oralternatively, tags may be located on an object, such as a piece ofequipment, and movement or presence of the object with respect to theone or more antennas can be detected through the signals received by theone or more antennas.

During implementation of an RFID system, an antenna receives signalsfrom one or more tags when a tag is within an operating range or acertain physical proximity to the antenna. A tag detection signalindicates a presence of the tag within an operating range of the antennaand may be transmitted by the antenna to other components within an RFIDsystem. The antenna may receive signals when a tag enters the operatingrange of the antenna and throughout the duration that the tag remains inthe area of the operating range. Additionally, the antenna may stopreceiving signals when the tag is no longer present within the operatingrange. Thus, the tag detection signals may be analyzed in order toidentify event information, such as a tag entering, remaining, and/orleaving a region proximate to an antenna. By including multiple antennaswithin an RFID system, tag detection signals from the multiple antennasmay be analyzed to identify event information, such as when a tag movesfrom the operating range of one antenna to the operating range ofanother antenna. In this manner, movement of an object or a person maybe tracked by analyzing the tag detection signals from the multipleantennas. For example, an RFID system having one or more antennas oneither side of a doorway may be used to track movement of a personassociated with a tag across the doorway by identifying, from tagdetection signals transmitted by the antennas, a direction of movementof the person such as the person entering or exiting the room.

In some embodiments, time information associated with a tag detectionsignal may identify a time when the tag detection signal was received bya sensor system. For example, a sensor system may be configured toidentify the time when signals related to a tag detection signal arereceived by an antenna and provide a timestamp associated with the tagdetection signal. Additionally or alternatively, a tag may be configuredto transmit time information, and the time information may be receivedby an antenna in association with a tag detection signal. In someembodiments, a tag detection signal may include such time information,while in other embodiments, a separate time signal containing such timeinformation may be transmitted by a tag. For example, a tag may transmita timestamp signal when the tag transmits a response signal, and anantenna may receive both the timestamp signal and the response signal.Regardless of the mode of obtaining time information associated with tagdetection signals, analysis of the time information and the tagdetection signals may provide additional event information than throughanalysis of only the tag detection signals. Event information, derivedfrom the tag detection signals, may then include a time associated witha particular event, such as a time when a person enters a room, or anamount of time a person spends in a room. In some embodiments,identification of an event may include comparing time informationassociated with a tag detection signal to time information associatedwith a stored tag detection signal.

The inventors have further recognized that in conventional operation ofRFID systems that include processing of signals to determine eventinformation, the tag detection signals are transmitted from the sensorover a network to a device that performs the processing. Depending onthe geographical locations of the sensors and the processing device,transmission of the signals may occur over a local area network or awide area network. The location of the additional device may depend onthe type of environment the sensors are deployed and access of thesesensors to a reliable communication network in order to transmit thesignals to a remote device.

When RFID systems are deployed at locations with limited networkconnectivity, such as a low network bandwidth and/or a network withintermittent connectivity, transmission of signals to a remote devicefor further filtering and/or processing for event identification maybecome limited. Such reduced network connectivity may limit theperformance of RFID systems to report events occurring where the sensorsare deployed. An RFID system might transmit limited information bysuppressing duplicate tag reads or tag detection signals and onlytransmitting unique tag IDs identified by antennas. However, suchoperation of RFID systems may limit the types of applications the RFIDsystem can be deployed.

The inventors have appreciated that performance of RFID systems may beimproved by reducing the amount of information transmitted by sensors toa remote device in order to accommodate limited network connectivitywhile retaining the processing capabilities to generate substantialinformation and analysis on objects that are being tracked. The amountof information may be reduced by sending messages, indicating events ata location, rather than every tag detection signal. Accordingly, someembodiments described herein relate to a sensor system configured toperform processing tasks on signals received by the sensor system toidentify events related to the signals and transmit event informationrelated to the events over a network to a server. By transmitting theevent information instead of the tag detection signals, the amount ofinformation transmitted is reduced while retaining functionality of thesensor system to detect movement and/or presence of tagged objects. Theprocessing performed by the sensor system to filter the amount ofsignals to transmit over a network allows the RFID system to performunder a variety of network conditions, including transmitting ofinformation over a wide area network. Additionally, in some embodiments,a sensor system may include one or more buffering capabilities tofurther improve transmission capabilities of a sensor system over anetwork.

The inventors have further appreciated that the implementation and useof an RFID system can be improved by providing techniques that allow forconfiguration of RFID sensors remotely. Accordingly, some embodimentsdescribed herein relate to a server or storage device configured toreceive messages containing information from sensor systems, where theinformation may include event information identified by the sensorsystem and configuration parameters of the sensor system. The server mayfurther analyze the event information and/or features of the signalsrelated to the event information to confirm events and evaluate theconfiguration parameters of the sensor system. Event information fromthe message may be analyzed by identifying a portion of one or moreevents that consolidates a number of occurrences for an event type.Consolidating the number of occurrences for an event type may furtherreduce the amount of event information stored. As an example, if eventinformation from a sensor system indicates a tag crossing an entrywaymultiple times over a certain amount of time, then the server mayfurther analyze the event information and identify the tag as crossingthe entryway in one direction such as entering a room. Events may bestored on a server and accessed by a user, such that the user can viewevent notifications, alerts, and/or status updates of the sensor system.Event information may include inventory management and/or meetingattendance. In some embodiments, processing of a message may includeanalyzing one or more events and features of the signals to identifyinformation indicative of a status of the sensor unit. A messageindicating the status of the sensor unit may be presented to a user.

Additionally, RFID sensor systems deployed at multiple locations may beused to detect and track objects at the multiple locations. Eventsderived by processing tag detection signals received by the sensors atthe multiple locations may be collected and stored on a server.Collecting and analyzing event information from multiple locations mayallow for more accurate processing or tracking of objects by having theevent information accessible from one location. In this manner, relatedevent information may be compared among the multiple locations as partof an analysis of the events. For example, as a person moves from onelocation to another, this movement may be detected by the multiplesensor systems such that events associated with the person may beobtained.

Components of a sensor system including sensors and the sensor units maybe configured by providing one or more configuration parameters to theappropriate component of the sensor system. Configuration of a sensorsystem having a sensor unit and one or more sensors may be achievedlocally and/or remotely through a server. Configuration parameters maybe updated based on information of a received message and/or managed bya user accessing the server. Information generated by the server may bereported back to the sensor system including further analysis of theevents and updates to configuration parameters may be transmitted backto the sensor system. The sensor units in one or more location may beupdated by commands sent from the server. The server may determine whichcommands to send in any suitable way, including based on express userinput identifying configuration parameters for sensor systems inspecific locations or by automated processing of events. The updatedconfiguration parameters may be used to change the mode of operation ofone or more antennas.

An exemplary RFID system is illustrated in FIG. 1. The exemplary RFIDsystem includes a reader or sensor unit having antennas 104 a-f deployedat locations to detect tags 100 a-b associated with objects. In thisexample the objects are people who are using tags, illustrated here aswearers 102 a and 102 b. In some embodiments, the RFID system isconfigured as an Active Reader Passive Tag (ARPT) system, and, in someembodiments, the RFID system is configured as an Active Reader ActiveTag (ARAT) system. An antenna may receive a signal from a tag when thetag is proximate to the antenna. For example, user 102 b wearing tag 100b is within a proximate range of antenna 104 e such that antenna 104 emay receive signals from tag 100 b. In this manner, antennas may bearranged to track movement of tagged objects by placing the antennas atcertain locations. For example, antennas 104 a, 104 b, 104 c, 104 d arearranged on either side of an entryway to a room, where antennas 104 aand 104 c are located outside of the room and antennas 104 b and 104 dare located inside of the room in order to detect a tag worn by a personwho is either entering or leaving the room, such as wearer 102 a wearingtag 100 a.

As part of a sensor system deployed at a location, one or more antennasmay be in communication with a sensor unit that receives tag detectionsignals from the one or more antennas, where the tag detection signalsare based on the signals received by the antenna. The sensor unit mayinclude ports to receive connections to the antennas, at least oneprocessor, and at least one memory. Additionally, sensor unit may be incommunication with a network, such as a local area network or a widearea network.

Any suitable number of antennas may be in communication with a sensorunit. Communication between an antenna and a sensor unit may occur inany suitable way, including wired and wireless communication. Suchcommunication techniques may include a cabled connection, wireless localarea network (LAN), a gateway to a wide area network, and cellularnetworks. For example, antennas 104 a, 104 b, 104 c, and 104 d are incommunication with sensor unit 106 a such that tag detection signalsfrom antennas 104 a, 104 b, 104 c, and 104 d are transmitted to sensorunit 106 a in response to an antenna receiving signals from a tag. Asshown in FIG. 1, user 102 a wearing tag 100 a is closer to antennas 104b and 104 d, and antennas 104 b and 104 d may transmit to sensor unit106 a tag detection signals indicating the presence of tag 100 aproximate to antennas 104 b and/or 104 d. Similarly, antennas 104 e and104 f are in communication with sensor unit 106 b, and antenna 104 e maytransmit tag detection signals indicating tag 100 b worn by user 102 bis within a detection range of antenna 104 e.

A sensor system may identify events by processing the tag detectionsignals, and the events may be transmitted by the sensor system to aserver over a broad geographical area such as over a wide area network.In some instances, a sensor system may include a transmitter to transmita message indicating the identified events. In some embodiments, thetransmitter may be configured to transmit the message indicating theevents over a wide area network to a server. In some embodiments, thetransmitter may be configured as a local area network transmitterconnected to a gateway that transmits over a wide area network. Forexample, a wireless link to a gateway may be used to transmitinformation over a wide area network to a server. As illustrated in FIG.1, sensor units 106 a and 106 b communicate with server 110 over a widearea network. By processing the tag detection signals to identify eventsinstead of transmitting each tag detection signal, the amount ofinformation transmitted in a message from a sensor unit to a remoteserver can be reduced, and the ability of the RFID system to reportdetected events can be improved.

Upon receipt of a message indicating identified events, informationabout the identified events may be stored in one or more event data setswithin the server. For example, server 110 contains one or more eventdata sets 115 configured to store events identified by sensor units 106a and 106 b. Event data sets 115 may be configured in any suitablemanner depending on the implementation of the RFID system and mayinclude events identified from any number of locations with deployedsensor systems.

In some embodiments, server 110 is configured as a cloud service suchthat information stored on server 110 may be accessed remotely throughone or more user interfaces by users to view information stored in theevent databases. As illustrated in FIG. 1, user 102 c may access one ormore event databases 115 through user interface 125 configured toconnect to server 110.

Additionally, server 110 may store one or more configuration parameters120 for operating the sensor systems. The one or more configurationparameters may include parameters used to operate one or more sensorsystems, including parameters used to operate one or more sensor unitsassociated with antennas having transmission power and reception signalsensitivity for individual antennas, antenna placement information, andcommissioning and decommissioning of individual antennas. Additionally,configuration parameters may include operational parameters for one ormore sensor units, including indicator functions for identifying events,parameters for identifying events such as predetermined time intervals,heartbeat communication intervals, and data transmission intervals.Relevant configuration parameters may be transmitted to sensor units 106a and 106 b and used to analyze tag detection signals for eventidentification. For example, configuration parameters relevant forantennas 104 a-d and sensor unit 106 a may be transmitted to sensor unit106 a.

Configuration parameters may be updated on a server located remotelyfrom a sensor system, and subsequent synchronization of configurationparameters relevant to the sensor system may occur, allowing for remoteconfiguration of the sensor system. In this manner, multiple sensorsystems may be configured and managed through a centralized system byaccessing a server that stores configuration parameters for the multiplesensor systems. As in some embodiments, server 110 is configured as acloud storage device such that configuration parameter(s) 120 may beaccessed remotely through user interface 125 by user 102 c to viewand/or modify one or more configuration parameters.

Using the techniques described herein, a centralized system may improveease of deployment of RFID systems by allowing for delegation ofinstallation tasks for sensor systems—such as installing the sensorsystem, attaching and detaching antennas, and connecting power—topersonnel who do not require training on the configuration process forthe sensor systems. Conventional RFID systems may be setup once duringcommissioning of sensor systems and require a user at the location toreconfigure the sensor system to reflect any changes to theconfiguration parameters. A centralized system allows for remotemodification of configuration parameters such that a user canreconfigure multiple sensor systems without having to be on-site toaccess the sensor systems directly. Additionally, a centralized systemallows for an RFID system to operate in a closed loop, with commandssent from the centralized system to sensor units. For example, suchcommands can minimize the chance of misappropriation of the sensorsystems because, in some embodiments, the sensor systems can bedecommissioned remotely by a command sent from the centralized systemwhenever needed.

According to the techniques of the present invention, a sensor systemmay include processing components implemented to process the receivedtag detection signals and store at least some of the tag detectionsignals. The processing components may process the tag detection signalsand identify events such as the presence of an object in an area andmovement of an object from one area to another area, including crossingan entryway of a room. A functional block diagram of an exemplary asensor system and server is illustrated in FIG. 2. FIG. 2 illustratesrepresentative functional portions of sensor system 226, which may beimplemented in any suitable form, as embodiments are not limited in thisrespect. As depicted, exemplary sensor system 226 includes signalanalyzer 228, event identifier 230, and message generator 236. Each ofthese processing components of sensor system 226 may be implemented insoftware, hardware, or a combination of software and hardware. Althoughthe example operating environment of FIG. 2 depicts signal analyzer 228,event identifier 230, and message generator 236 implemented together onsensor system 226, this is only an example; in other examples, any orall of the components may be implemented on one or more separatemachines, or parts of any or all of the components may be implementedacross multiple machines in a distributed fashion and/or in variouscombinations. It should be understood that any such component depictedin FIG. 2 is not limited to any particular software and/or hardwareimplementation and/or configuration.

In some embodiments, signal analyzer 228 may be configured, such asthrough program instructions executed by one or more processors ofsensor system 226, to analyze tag detection signals received by antenna204 and determine information associated with the tag detection signals.That associated information may include tag identification information,time information, one or more features of the signals, and configurationparameters of sensor system 226. The tag identification informationassociated with a tag detection signal may uniquely identify the tagthat transmitted the signals received by an antenna. Information storedon the tag may include identification information, such as a tag ID, andmay be transmitted to antenna 204 when the tag is proximate to antenna204. In some embodiments, time information associated with when the tagis detected by antenna 204 may be acquired. The time information mayinclude a timestamp provided by a sensor unit that indicates a timeassociated with a received signal. In some embodiments, signal analyzer228 may provide a timestamp or other suitable time indicator uponreceiving a tag detection signal. In such embodiments, signal analyzer228 may communicate with a clock of sensor system 226 or otherwisecontain components that can access time information in order to identifytime information associated with a received tag detection signal.Additionally, antenna 204 may transmit one or more features of thesignals received by antenna 204 as part of a tag detection signal. Suchfeatures may include a power used to transmit interrogation signals fromantenna 204 and the strength of a signal received by antenna 204 inresponse to the interrogation signals.

In some embodiments, a tag detection signal may also include one or moreconfiguration parameters of sensor system 226, such as informationidentifying the location of antenna 204 and/or configuration ofprocessing tasks for tag detection signals provided by antenna 204. Thelocation and/or operational mode of antenna 204 may be used insubsequent processing to identify events from the tag detection signalstransmitted by antenna 204. Such modes may include a presence mode wherea tag's arrival or exit from a proximate range of an antenna arereported as events, a muster mode where a tag is first detected within aproximate range of an antenna is reported as an event, and portal modewhere a tag is identified as crossing from a proximate range of oneantenna to a proximate range of a second antenna. Portal mode could beused to detect a tag crossing an entryway to a room where a firstantenna is located inside the room and a second antenna is locatedoutside of the room. In such embodiments, the first antenna's modeindicates a location on the inside of the room and the second antenna'smode indicates a location on the outside of the room. In someembodiments, configuration parameter(s) 242 for individual antennas maybe stored within sensor system 226 such that signal analyzer 228 mayretrieve a configuration parameter for a tag detection signal. In suchembodiments, a tag detection signal may include identificationinformation for antenna 204, and signal analyzer 228 may retrieve alocation and/or a mode for antenna 204 from configuration parameter(s)242.

In some embodiments, signal analyzer 228 may provide information toevent identifier 230 about the tag detection signal it has analyzed. Insome embodiments, signal analyzer 228 may provide tag identificationinformation, time information, and/or antenna configuration parameters.Event identifier 230 may further process the information provided bysignal analyzer 228 in order to identify one or more events related tothe presence of a tag at a location of antenna 204. Information providedby signal analyzer 228 may be used by event identifier 230 to determinethe type of processing and analysis to perform to evaluate whether anevent has occurred. In some embodiments, signal analyzer 228 mayidentify, in response to receiving a tag detection signal an antenna, anoperational mode for the antenna, and the operational mode may determinesubsequent processing of the tag detection signal by event identifier230.

In some embodiments, tag detection signals stored in sensor system 226may be used to identify events related to an incoming tag detectionsignal from antenna 204. Within sensor system 226, tag detection signalsmay be selectively stored in one or more tag signal data sets 224. Insome embodiments, stored tag detection signals in one or more tag signaldata sets 224 may include previously received tag detection signals, andin some embodiments, the one or more tag signal data sets 224 mayinclude tag detection signals relevant to previously identified events.

Tag detection signals may be stored in one or more tag signal data sets224 in any suitable configuration. In some embodiments, stored tagdetection signals may be organized based on antenna information such asthe antenna's location and/or mode of operation used to identify a typeof event associated with the stored tag detection signals. Someembodiments may configure one or more tag signal data sets 224 as one ormore tag read lists, where each tag read list is associated with theidentification of a type of event and the tag detection signals storedas entries in the read list are related to the type of event. In thismanner, relevant tag detection signals are stored in a tag read list andcan be searched by accessing the tag read list. Additionally oralternatively, one or more tag signal data sets may be organized basedon one or more sensor systems and/or location of one or more antennas.By constructing tag signal data sets based on sensor systems, eventidentifier 230 may process a tag detection signal received from a sensorsystem by accessing information relevant to other tag detection signalsin the sensor system.

Event identifier 230 receives information related to an incoming tagdetection signal provided by signal analyzer 228 and, by processing theinformation, may identify an event. An event may be identified in anysuitable manner according to the desired use of the RFID system. Theevents may be identified based on multiple tag identification signals,which may entail tag identification signals collected by the sameantenna at different times or at different antennas at the same ordifferent times. In some embodiments, an event is identified when a tagdetection signal corresponding to a tag includes tag identificationinformation that matches the tag identification information of a tagdetection signal stored in one or more tag signal data sets 224. In someembodiments, an event is identified when a tag detection signalidentifying a tag is transmitted by a first antenna and a tag detectionsignal identifying the tag is transmitted by a second antenna. Someembodiments may identify events based on time information associatedwith tag detection signals, where an event is identified by comparingtime information for an incoming tag detection signal to timeinformation associated with one or more tag detection signals stored inone or more tag signal data sets 224. In some embodiments, an event isidentified by comparing a difference between the time information of anincoming tag detection signal with time information associated with astored tag detection signal to a time interval. The time interval may bea predetermined time interval and/or a configurable parameter where thevalue can be changed while the sensor system is in operation. Theincoming tag detection signal and the stored tag detection signal mayhave distinct tag identification information. Since an antenna continuesto receive signals from a tag located proximate to the antenna, someembodiments may identify an event by an absence of a tag detectionsignal corresponding to the tag for an amount of time exceeding a timeinterval.

Some embodiments may identify, by processing a tag detection signal, oneor more stored tag detection signals to remove from one or more tagsignal data sets 224. In some embodiments, a stored tag detection signalmay be modified to reflect an identified event. By updating the storedtag detection signals based on identified events, the one or more tagsignal data sets 224 may improve the speed or accuracy of identifyingsubsequent events. For example, as a person crosses an entryway into aroom with an antenna located on the outside and an antenna located onthe inside of the room, a tag worn by the person may be detected by theoutside antenna followed by the inside antenna, and an event indicatingthat the person is incoming may be identified. As a result, signalsindicating the tag received by the outside antenna and information froma related tag detection signal may be stored in a tag signal data set,which may be used to identify movement of the person across the entrywaywhen signals indicating the tag are received by the inside antenna.After identifying that the tag, and thus the person, has moved insidethe room, the tag signal data set may be updated to reflect the movementof the tag by removing from the tag signal data set the stored tagdetection signal related to the event from the outside antenna. Thestored tag detection signal may be deleted from the memory of the sensorunit.

In some embodiments, a stored tag detection signal may be removed from atag signal data set based on time information associated with the storedtag detection signal. Some embodiments may update a tag signal data setby removing a stored tag detection signal when the time informationassociated with the stored tag detection signal is greater than apredetermined time interval indicating that a certain amount of time haspassed since the stored tag detection signal was received. The storedtag detection signal may be deleted from the memory of the sensor unitwhen a difference between time information associated with the storedtag detection signal and a current time is greater than a predeterminedtime interval.

Stored tag detection signals identified for deletion from the sensorunit's memory may include tag detection signals identified as “orphaned”tag detection signals such as tag detection signals indicating signalsreceived by a single antenna. Orphaned tag detection signals may beidentified when a sensor system is operating in a portal mode and thereis a discrepancy between detection inside and outside a room or area. Atag detection signal may be identified as an orphaned tag detectionsignal when a difference between the time information associated withthe tag detection signal and the time information associated with astored tag detection signal is greater than a time interval. Tagidentification information associated with the tag detection signal maybe distinct from tag identification information associated with thestored tag detection signal, indicating a discrepancy between in tagidentification information for the two tag detection signals.

In some embodiments, information related to an identified event may bestored in one or more event data sets 234. Information stored in eventdata set(s) 234 may include tag identification information associatedwith the event, a type of event, time information associated, and signalfeatures related to the tag detection signal that indicated the event.Event data set(s) 234 may be organized and structured by type of event,sensor system, and/or events identified for upload to a device orserver. While information related to events identified by processing tagdetection signals by sensor system 226 may be stored locally in one ormore event data sets 234, the information related to events may also betransmitted to another device or system, such as server 210. Sensorsystem 226 may construct event data set(s) 234 to indicate the eventinformation has been transmitted to server 210 and the eventinformation, which may be more recent, to be transmitted.

Some embodiments may issue an alert to a user of the RFID system inresponse to the identification of a particular event type, includingerror signals, unauthorized movement of objects or users, and/or safetynotifications. In some embodiments, one or more tag signal data sets mayidentify tags associated with objects or users with limited orrestricted access to certain locations. Some embodiments have tag signaldata sets that include tag identification information for certain tagsand types of alerts to issue if a tag detection signal having tagidentification information stored in the tag signal data sets isidentified. In this manner, a processing component may issue an alert inresponse to identification of an event type which may be determined bycomparing tag identification information associated with an incoming tagdetection signal to tag identification entries in the tag signal datasets. The alert may be reported by sensor system 226 through userinterface 244 having any suitable indicator, including one or moreaudible and/or visible indicators such as an alarm and indicator lights.The alert may indicate any suitable type of event. For example, alertsmay indicate access to a certain area, such as a room, by a person whohas restricted access to the room or area. The ability to processinformation locally on the sensor system allows for the detection oftags even when there is an absence of connection to a remote device,such as server 210.

Additionally, server 210 may provide to a sensor system one or more tagsignal data sets used for identifying events that indicate an alert tobe issued. The one or more tag signal data sets may indicate privilegesettings for certain tags or users associated with certain tagsidentified in the one or more tag signal data sets. Some embodiments mayhave tag signal data sets, which may include whitelists and/orblacklists of tag identification information such as a tag ID. When anevent is identified by event identifier 230, an alert may be issuedlocally by sensor system 226. Information related to the event may bestored in an event data set identified for upload to server 210,allowing a user to remotely receive the event and/or the alert. In someembodiments, event information related to an alert may be furtherprocessed by server 210 to verify the occurrence of the event and/oridentify more details about the status of the alert.

Message generator 236 may construct a message including informationprovided by event identifier 230 and/or one or more event data sets 234.Message information may include event information, status of the sensorsystem, and alert notifications. Message generator 236 may constructmessages to include event information that has been added to event dataset(s) since a previous message was transmitted, allowing for recentlyidentified events to be synchronized with a remote device. In someembodiments, a message may include diagnostic information such ascondition of a power supply, backup battery status, sensor systemtemperature, intrusion detection, network connectivity status, andout-of sequence data. In some embodiments, message generator mayconstruct messages to include information about incoming signals to thesensor system such as custom signals from a user pushing a button onuser interface 244. Additionally, some embodiments may includeperformance metrics of individual antennas such as features and/orquality of the signals received by the individual antennas. In someembodiments, a message may indicate a periodic signal to indicate astatus of the sensor system to a device receiving the message. Suchperiodic messages may be generated and transmitted at configurableintervals and may include heartbeat communication techniques, allowing aremote device lacking the ability to directly interrogate a connectedsensor system to monitor the status of a sensor system through thereceived periodic messages.

Messages constructed by message generator 236 may be provided totransmitter 238 which transmits the message to server 210. In someembodiments, transmitter 238 is configured to transmit messages across awide area network to server 210. To account for intermittentconnectivity when transmitting messages across a network with varyingquality, sensor system 226 may include a data buffer configured to storea portion of a message during transmission to prevent loss of outgoingmessages from sensor system 226. The data buffer may be configured tostore a portion of a message when the transmitter is unable to transmitthe message. By providing a data buffer as part of transmittingmessages, an RFID system is able to handle both transient outages incommunication as well as bandwidth restrictions when transmitting data.In some embodiments, the data buffer is configured to transmit a messagewhen sensor system 226 is in communication over a network to server 210and to store a portion of the message yet to be transmitted whencommunication is interrupted. Any suitable number and/or types of databuffers may be provided to a sensor system to handle intermittentnetwork connection and network quality and improve performance of anRFID system.

In some embodiments, in-memory buffering techniques may be used bysensor system 226 such that data collection and tag detection signalprocessing are separate from message generation and transmission.In-memory buffering may allow for processing of tag detection signals tooccur at a different processing speed than the transmission of amessage, reducing the impact of variations in message transmission speedon processing speed for incoming tag detection signals. Some embodimentsmay employ on-disk buffering techniques to further resolve networkconnectivity issues by temporarily storing unsent data in a memory suchas a flash memory configured to reestablish transmission of the datawhen connectivity returns. The memory may be further configured tomaintain the sequence of the original message during intermittentnetwork connectivity such that server 210 received the message in theintended sequence. In the event of failure of sensor system such as ahardware malfunction or failure, the on-disk buffer containing thestored message can be transferred to a replacement device, minimizingthe loss of information obtained by the sensor system.

Messages may also be received by sensor system 226 from server 210.Receiver 240 associated with sensor system 226 may be configured toreceive messages transmitted by server 210 over a network. In someembodiments, receiver 240 may be configured to receive messages fromserver 210 across a wide area network. Any suitable technique forestablishing communication and transmission of messages from server 210to sensor system 226 may be used.

Some embodiments relate to techniques for configuring a sensor systemand a server when the sensor system is not directly accessible by theserver. In such embodiments, the server is unable to provide messagesdirectly to the sensor system. Communication between the server and thesensor system can be established by configuring the sensor system totransmit messages to the server and the server to transmit a responsemessage to the sensor system in response to receiving a message from thesensor system. Configuring outgoing communication from a sensor systemto a server that signals the server to provide a response message allowsfor bidirectional communication between the deployed sensor system andserver. These communication techniques may be implemented in RFIDsystems where communication from the server to the sensor system isblocked, such as by network operators (e.g., blocking of a wide areanetwork by mobile operators). Such communication techniques may bereferred to as heartbeat communication. In some embodiments, messagesmay be periodically generated and transmitted by the sensor system. Atime interval for transmitting messages by the sensor system may be setat predetermined intervals or at configurable intervals provided by aconfiguration parameter.

Such techniques may be implemented in RFID systems where one or moresensor systems are inaccessible from outside the local network of theone or more sensor systems. In embodiments where sensor system 226 isinaccessible directly from server 210, sensor system 226 may receive amessage from server 210 in response to sensor system 226 transmitting amessage to server 210. The transmitted message may indicate to server210 that a response message be transmitted to sensor system 226. Theresponse message may contain information stored on server 210 such asconfiguration parameters 215 and events stored in event databases 220.In some embodiments, the transmitted message may include informationidentifying sensor system 226, and server 210 may be configured to usethe identification information to transmit a response message forreceipt by sensor system 226. In some embodiments, messages may beperiodically generated and transmitted by sensor system 226 to server210. A time interval for transmitting messages by sensor system 226 maybe a predetermined interval or a configurable interval set by aconfiguration parameter.

A response message transmitted by server 210 to sensor system 226 mayinclude event information. Receiver 240 may then direct eventinformation from the response message to event identifier 230. Eventidentifier 230 may update the event information stored in event datasets 234. In this manner, event information stored on server 210 may besynchronized with event information stored on sensor system 226. Eventidentifier 230 may provide a message containing the event informationfrom the response message to user interface 244. For example, server 210may determine that certain event information indicates an alertsituation and provide a message to sensor system 226 to indicate astatus alert such as a switching on an alert light.

According to the techniques of the present invention, a serverconfigured to receive messages from one or more sensor systems mayinclude processing components implemented to process the receivedmessages identifying events detected by a sensor system and features ofsignals associated with the events, update one or more configurationparameters for a sensor system, and generate a message to be transmittedto a sensor system. A functional block diagram of an exemplary serverconfigured to receive messages from a sensor system is illustrated inFIG. 3. The exemplary operating environment includes server 310, whichmay be implemented in any suitable form, as embodiments are not limitedin this respect. As depicted, exemplary server 310 includes messageanalyzer 326, signal feature analyzer 328, event visualizer 330,configuration manager 335, and message generator 332. Each of theseprocessing components of server 310 may be implemented in software,hardware, or a combination of software and hardware. Although theexample operating environment of FIG. 3 depicts message analyzer 326,signal feature analyzer 328, event visualizer 330, configuration manager335, and message generator 332 implemented together on server 310, thisis only an example; in other examples, any or all of the components maybe implemented on one or more separate machines, or parts of any or allof the components may be implemented across multiple machines in adistributed fashion and/or in various combinations. It should beunderstood that any such component depicted in FIG. 3 is not limited toany particular software and/or hardware implementation and/orconfiguration.

In some embodiments, message analyzer 324 may be configured, such asthrough program instructions executed by one or more processors ofserver 310, to analyze messages received by receiver 322 from a sensorsystem component such as sensor unit 306 and determine the type ofinformation associated with the message such as events, alertnotifications, sensor status, features of signals, and configurationparameters. Event information may include the type of event and the timethe event was detected by a sensor system. Any other suitable type ofinformation may be communicated in a message from a sensor unit, and maybe extracted by message analyzer 324. Other examples include operatingparameters of the sensor unit and/or characteristics of signalsmeasured, such as the signal strength or signal to noise ratio of thetag detection signals used in identifying an event.

Message analyzer 324 may provide relevant event information to eventanalyzer 326 and signal feature information to signal feature analyzer328. In some embodiments, message analyzer 324 may analyze the stabilityof the overall infrastructure of the RFID system including the qualityof the network connection. In some embodiments, message analyzer 324 mayanalyze the operational status of one or more sensor systems, includingpower supply, backup power supply, and/or an alert notification such asan intrusion alert.

In some embodiments, event analyzer 326 may be configured, such asthrough program instructions executed by one or more processors ofserver 310, to analyze event information received by message analyzer324 further to distinguish and filter the event information. In someembodiments, event analyzer 326 may analyze event information toidentify redundant information, and event analyzer 326 may process theevent information to reduce and/or remove the redundant information. Byreducing the amount or redundant information present in the eventinformation, the potential impact for misconfiguration of a sensorsystem to introduce artifacts may be reduced. Events identified by asensor system may include multiple movement events recorded within ashort time period and consist of redundant or unnecessary information.By identifying a portion of the events that consolidates a number ofoccurrences for an event type, the amount of event information may bereduced. For example, a sensor system configured to track movementinside and outside of a room may identify tag movements consisting of atag moving inside, then outside, followed by inside the room over ashort period of time. Event analyzer 326 may analyze such a sequence ofevents and determine that a single movement into the room was made bythe tag. Some embodiments may process event information based onfeatures of the signals, including signal quality and/or strength usedto identify the events such that signals having a certain quality areused to identify events.

Events analyzed by event analyzer 326 may be stored in one or more eventdatabases 315. Information stored in event database(s) 315 may includeinformation from multiple sensor systems and sensor systems at multiplelocations. A user may view the event information stored in one or moreevent databases through event visualizer 330 which may be configured toaccess the event information and present the information on userinterface 340. In this manner, a user may access the event informationstored on server 310 over a network through any suitable user interfaceor device without having to be physically located where the sensorsystems providing the event information are deployed.

In some embodiments, signal feature analyzer 328 may be configured, suchas through program instructions executed by one or more processors ofserver 310, to analyze features of signals received by one or moreantennas. Signal feature analyzer 328 may analyze features of thesignals received by antennas and update one or more configurationparameters for the antennas based on the analysis of the features.Configuration parameter(s) 320 stored on server 310 may be updated toreflect the analysis of signal feature analyzer 328. In someembodiments, signal feature analyzer 328 may identify antennas acquiringsignals with a low strength and update one or more configurationparameters such as the power setting for the antennas. By having server310 analyze the signals received by antennas to evaluate theconfiguration parameters of the antennas, updating the configurationparameters may improve overall performance of the RFID system and canautomatically occur without involving direct input by a user. However,it should be appreciated that, in other embodiments, some or all of theanalysis described as performed in the analyzers 324, 326 and 328 couldalternatively or additionally be performed in one or more of the sensorunits.

Some embodiments may analyze both event information and signal featuresto identify one or more configuration parameters to update. Signalfeature analyzer 328 may include event information provided by eventanalyzer 326 during analysis of the signals received by antennas relatedto the event information. In some embodiments, signal feature analyzer328 may identify a quality of signals related to certain events andupdate the configuration parameters for antennas that received thesignals. For example, event information either provided by a sensorsystem or event analyzer 326 may indicate stray or “orphaned” tagdetection signals such as tag detection signals indicating signalsreceived by a single antenna. Orphaned tag detection signals may beidentified when a sensor system is operating in a portal mode and thereis a discrepancy between detection inside and outside a room or area.Combining analysis of event information and signal features may improvedetection of events by an RFID system. As an example, events may bedistinguished by signal strength such that events having a high signalstrength may indicate a movement by a user or object to store in eventdatabase(s) 315, while events having a low signal strength indicate anorphaned tag detection signal and the associated event may be identifiedas not indicating movement of the user or object and may be removed fromevent database(s) 315.

Additionally or alternatively, a power setting for one or more antennasreceiving lower strength signals may be adjusted to improve signalstrength and/or event identification. For example, a large number oforphaned tag detection signals may indicate that an antenna's powersetting is too high, and the antenna's configuration parameters may beupdated to lower its power setting. As another example, a majority ofsignals received by an antenna may have low signal strength, indicatingthat the power setting of the antenna is too low, and configurationparameters may be updated to increase the antenna's power setting. Inanother example, the signal strength of signals received by an antennamay be proximate to the detection sensitivity setting for the antenna,and data quality may be improved by increasing the sensitivity setting.

Additionally or alternatively, a user may access one or moreconfiguration parameters 320 stored on server 310 and edit or update theone or more configuration parameters 320 through configuration manager335. Configuration manager 335 may provide configuration parameters touser interface 340 where a user can view, add, and/or modify one or moreconfiguration parameters, and configuration parameter(s) 320 stored onserver 310 may be updated to reflect any changes. In some embodiments, auser may have limited access to configuration parameters for certainsensor systems, allowing for configuration of the RFID system to berestricted to some individuals.

In some embodiments, message generator 328 may be configured, such asthrough program instructions executed by one or more processors ofserver 310, to construct a message based on event information,configuration parameters, alert notifications, and/or status signalsrelevant to a sensor system. The sensor system may include sensor unit306 and antennas 304 a-b. Although two antennas are shown in FIG. 3, anysuitable number of antennas may be included in a deployed sensor system.A message may contain updates to event database(s) 315 identified byevent analyzer 326 and/or configuration parameter(s) 320 identified bysignal feature analyzer 328. Some embodiments may implement heartbeatcommunication techniques where sensor unit 308 may transmit a message toserver 310. The message may include a query related to whether there areconfiguration updates available. If there are configuration updatesavailable, then message generator 332 may generate a message in responseto the query, and server 310 may transmit the message containinginformation about the configuration updates to the sensor system. Inthis manner, bidirectional communication between sensor unit 306 andserver 310 may occur by allowing outgoing messages from sensor unit 306that signals server 310 to provide a response message to sensor unit306. These communication techniques may be implemented in RFID systemswhere communication from server 310 to sensor unit 306 is blocked (e.g.,blocking of a wide area network by mobile operators).

Transmitter 334 may be configured to transmit a message constructed bymessage generator 332 to a sensor system identified as the intendedrecipient for the message. In some embodiments, transmitter 334 is awide area network transmitter configured to transmit messages over awide area network. Some embodiments may include one or more databuffering techniques, such as techniques previously described in thecontext of sensor system 226, for transmitting messages by server 310 inorder to improve performance of communication between server 310 andsensor system when a network has bandwidth and/or connectivity problems.

Sensor system 226 and/or server 310 may be implemented as a singlestand-alone machine, or may be implemented by multiple distributedmachines that share processing tasks in any suitable manner. In someembodiments, sensor system 226 and/or server 310 may include one or moretangible, non-transitory computer readable storage devices storingprocessor-executable instructions, and one or more processors thatexecute the processor-executable instructions to perform the functionsdescribed herein. The storage devices may be implemented ascomputer-readable storage media (i.e. tangible, non-transitorycomputer-readable media) encoded with the processor-executableinstructions.

Components implemented with software may comprise sets ofprocessor-executable instructions that may be executed by the one ormore processors of sensor system 226 and/or server 310 to perform thefunctionality described herein. Components may be implemented asseparate components (e.g., implemented by hardware and/or software codethat is independent and performs dedicated functions of the component),or any combination of these components may be integrated into a singlecomponent or a set of distributed components (e.g., hardware and/orsoftware code that performs two or more of the functions describedherein may be integrated, the performance of shared code may bedistributed among two or more hardware modules, etc.). In addition, anyone of components of sensor system 226 and/or server 310 may beimplemented as a set of multiple software and/or hardware components.

In some embodiments, processing of tag detection signals by a sensorsystem may include identifying one or more types of events the sensorsystem is configured to detect. Sensors, as part of a sensor system, maybe positioned and arranged such that analysis of tag detection signalsmay identify a specific type of event. When a sensor system isconfigured to detect a particular type of event, it may be referred toas operating in a certain type of mode. Configuration informationrelated to operational mode and/or type of events detected by a sensorsystem may be stored on the sensor unit and/or on the sensors. Byidentifying the mode of a sensor system, tag detection signals may beanalyzed according to processing tasks specific to the mode. Someembodiments relate to sensor systems configured to operate in a portalmode where sensors are arranged on either side of an entryway andanalysis of tag detection signals may indicate that an object or personcrossing the entryway as a type of event. In this manner, a sensorsystem may operate in a mode referred to as a “portal mode.” As part ofthis analysis, one or more sensors may be designated as being located oneither side of the entryway, such as being located either inside oroutside a room. By using such location information for the sensors, thedirection of an object that crosses the entryway may be identified aseither entering the room or leaving the room. Sensors located inside aroom may be referred to as “IN” antennas, and tag detection signalsoriginating from these sensors may be analyzed according to a “PortalIN” process. While sensors located outside a room may be referred to as“OUT” antennas, and tag detection signals originating from these sensorsmay be analyzed according to a “Portal OUT” process.

Some embodiments relate to sensor systems configured to operate in a“presence” mode where analysis of tag detection signals includesidentifying types of events that include a tag's arrival and/ordeparture from a region in proximity to one or more sensors. As part ofthis analysis, time information related to when tag detection signalsare received may provide information about the times are which arrivaland/or departure occur. Tag detection signals from sensors associatedwith a sensor system configured to operate in presence mode may beanalyzed according to a “Presence” process.

In some embodiments, sensor systems may be configured to operate in a“muster” mode where analysis of tag detection signals includesidentifying types of events that include a tag's arrival at a certainlocation. Tag detection signals from sensors associated with a sensorsystem configured to operate in muster mode may be analyzed according toa “Muster” process. The above types of events are exemplary astechniques of the present application are not limited to the type ofevent detected by a sensor system. Additionally or alternatively, asensor system may be configured to operate in multiple modes and/oridentify multiple types of events.

As tag detection signals are received, the operational mode of thesensor system associated with the antenna that provided the tagdetection signal may be identified in order to determine how to processthe tag detection signal. Processing tasks may be determined based onidentification of the antenna that provided the tag detection signal.The sensor system may use the antenna identification information toidentify a set of processing tasks to perform that may identify aparticular type of event for the tag detection signal. One exemplaryembodiment for identifying processing tasks for event identificationrelated to a tag detection signal is illustrated in FIG. 4. Method 400may be performed, for example, by one or more components of sensorsystem 226 such as signal analyzer 228 and/event identifier 230,although other implementations are possible and method 400 is notlimited in this respect. Method 400 begins at act 410, when a tagdetection signal is received by sensor system 226. As discussed above, atag detection signal may be provided by an antenna based on signalsreceived by the antenna, where the signals are indicative of a tagproximate to the antenna.

At act 420, the tag detection signal may be analyzed, includingidentifying tag identification information, time information associatedwith the tag detection signal, and/or features of the signals receivedby the antenna related to the tag detection signal transmitted by theantenna. As discussed above, the tag identification information uniquelyidentifies the tag based on the signals received by the antenna. Timeinformation associated with the tag detection signal may include a timeindicator such as a timestamp provided by the sensor system in responseto receiving the signals. Features of the signals received by theantenna may include the strength of the signals received by the antenna.

At act 430, the antenna transmitting the tag detection signal may beidentified, including identifying one or more configuration parametersof the antenna such as a location of the antenna and/or operational modeof the antenna. In some embodiments, a tag detection signal provided byan antenna may include information about the antenna's configurationparameters and/or operational mode, while in some embodiments, theantenna's configuration parameters may be identified by accessingconfiguration parameters stored in a sensor system based on the antennaidentification information included in a tag detection signal.Identification of the antenna at act 430 may indicate subsequentprocessing tasks for analysis of the tag detection signal in act 420. Asillustrated in exemplary method 400, information identifying the antennaat step 430 may indicate processing tasks for the tag detection signalwhich may identify an event by Portal IN process 440, Portal OUT process450, Presence process 460, and/or Muster process 470. Each one ofprocesses 440, 450, 460, and 470 includes processing tasks to identify atype of event based on the tag detection signal, one or more stored tagdetection signals, and time information associated with the tagdetection signal and/or the one or more stored tag detection signals.For example, an antenna located inside of a room may be identified suchthat tag detection signals are further processed by Portal IN process440. Identification information for the antenna may indicate that theantenna is an IN antenna and tag detection signals associated with theantenna are processed according to Portal IN process 440. An eventidentified by Portal IN process 440 may relate to a tag's presence atthe location of the antenna inside the room, indicating that a userassociated with the tag as entered the room.

One exemplary embodiment for processing tag detection signals receivedfrom antennas configured to detect movement across an entryway byoperating in portal mode is illustrated in FIG. 5. Method 500 may beperformed, for example, by one or more components of sensor system 226such as signal analyzer 228 and/event identifier 230, although otherimplementations are possible and method 500 is not limited in thisrespect. Method 500 begins at act 510, at which a tag detection signalis received by sensor system 226. As discussed above, a tag detectionsignal may be provided by an antenna and include tag identificationinformation. At act 515, information associated with the tag detectionsignal may be used to identify whether the antenna providing the tagdetection signal is identified as either an antenna located in an areaand designated as an “IN antenna” or an antenna located outside the areaand designated as an “OUT antenna.” Information indicating how theantenna is designated during configuration may be used to determinesubsequent processing tasks.

Processing proceeds to act 520 when the antenna is identified as an INantenna, and, at act 520, tag identification information for the tagdetection signal is compared to information for stored tag detectionsignals received from one or more OUT antennas contained in a tag readlist. If there is an entry in the OUT tag read list corresponding to thetag identified by the tag detection signal, then processing proceeds toact 525 where time information for the entry in the OUT tag read list iscompared to a current time. If the entry in the OUT tag read list isrecent, then an incoming event is detected by act 530, and informationabout the event is sent to a server over a network and tag detectionsignals stored in an IN tag read list are updated to include the tagdetection signal. The tag detection signal is also added to the IN tagread list when the entry in the OUT tag read list is determined to notbe recent at act 525. Additionally, any tag detection signals identifiedto not be connected with a detected movement may be flagged as orphanedreads by act 545.

It should be appreciated that any suitable time interval may be used todetermine “recent” signals, and this interval may be different fordifferent processing modes. Moreover, the time interval may beconfigurable. The time interval may be included as part of configurationparameters 242 stored in sensor system 226. The time interval may beprovided as a configuration parameter to a server, such as servers 210and 310, and transferred to a sensor system by the server including thetime interval in a message and transmitting the message to the sensorsystem. The time interval may be used to determine whether a previoustag detection signal was recent when processing a current tag detectionsignal. Time information associated with the previous tag detectionsignal may be stored in tag signal data set 224 and may be compared totime information associated with a subsequent tag detection signal, suchas by determining an amount of time between the subsequent tag detectionsignal and the stored tag detection signal. When the amount of timebetween the two tag detection signals is less than the time interval,then the stored tag detection signal may be identified as “recent.” Insome embodiments, tag identification information for the stored tagdetection signal may be the same as tag identification information forthe subsequent tag detection signal, indicating that both tag detectionsignals correspond to the same tag. As a specific example, for somemodes, a tag detection signal at the IN antenna that occurs within 15seconds of a tag detection signal from an OUT antenna may be regarded asrecent. In other modes, in which, for example a person or object with atag may be expected to stay in a location for hours, a tag detectionsignal may be regarded as “recent” when the time between signals is lessthan an hour or some predetermined number of hours.

Similar processing tasks compare the tag detection signal to IN tag readlists when the antenna is identified as an OUT antenna by act 515. Acts550, 555, 560, and 565 mirror acts 520, 525, 530, and 540, respectively,and include processing steps to detect outgoing events to send to aserver over a network.

FIG. 6 illustrates an exemplary embodiment for processing tag detectionsignals by Portal IN process 440. Method 600 may be performed, forexample, by one or more components of sensor system 226 such as signalanalyzer 228 and/or event identifier 230, although other implementationsare possible and method 600 is not limited in this respect. Stored tagdetection signals stored in tag signal data set(s) 224 may be stored inthe form of one or more read lists. Portal IN process may identifyevents associated with a tag as incoming or entering a room based oncomparing the tag detection signal to stored tag detection signalsassociated with an OUT antenna. Processing of a tag detection signaltransmitted by an antenna configured in Portal IN mode includessearching an OUT tag read list for a tag entry identifying the tagcorresponding to the tag detection signal at act 615, detecting anincoming event when the tag entry has been added recently to the OUT tagread list at acts 625 and 630, and adding the incoming event to an eventlist for upload. When an incoming event is detected at act 630, theentry for the tag is removed from the OUT tag read list.

If the entry in the OUT tag read list is not identified as an old entryat act 640, then the tag detection signal is added to and IN tag readlist at act 660. However, if the entry in the OUT tag read list isidentified as old, then processing proceeds to act 645 to identifywhether the tag associated with the entry corresponds to a movement orpaired set of tag detection signals, or if the entry corresponds to anorphaned tag detection signal. If the entry corresponds to a movementpair by act 645, the entry is removed from the OUT tag read list by act650. If the entry corresponds to an orphaned tag detection signal, thena corresponding orphaned tag read is added to a list of events forreporting by act 655, and the entry is removed from the OUT tag readlist by act 650. Events identified by Portal IN process may be stored inone or more event data sets 234. Information related to these events maybe included in a message constructed by message generator 236 andtransmitted to a server.

It should be appreciated that any suitable time interval may be used todetermine “old” signals, and this interval may be different fordifferent processing modes. Moreover, the time interval may beconfigurable. As a specific example, for some modes, a tag detectionsignal at the IN antenna more than 5 minutes after of a tag detectionsignal from an OUT antenna may be regarded as old. In other modes, inwhich, for example a person or object with a tag may be expected to stayin a location for hours, a tag detection signal may be regarded as “old”when the time between signals is more than eight hours or somepredetermined number of hours.

In a similar manner, outgoing events may be detected by comparing thetag detection signal to stored tag detection signals from insideantennas in an IN tag read list. Exemplary processing tasks for a tagdetection signal transmitted by an antenna configured to operate inPortal OUT mode is illustrated in FIG. 7. Method 700 may be performed,for example, by one or more components of sensor system 226 such assignal analyzer 228 and/or event identifier 230, although otherimplementations are possible and method 700 is not limited in thisrespect. Stored tag detection signals stored in tag signal data set(s)224 may be stored in the form of one or more read lists. The portal OUTprocess may identify events associated with a tag as outgoing or leavinga room based on comparing the tag detection signal to stored tagdetection signals associated with an IN antenna.

Processing of a tag detection signal transmitted by an antenna operatingin Portal OUT mode includes searching an IN tag read list for a tagentry identifying the tag corresponding to the tag detection signal atact 715, detecting an outgoing event when the tag entry has been addedrecently to the IN tag read list of acts 725 and 730, and adding theoutgoing event to an event list for upload. When an outgoing event isdetected at act 730, the entry for the tag is removed from the IN tagread list.

If the entry in the IN tag read list is not identified as an old entryat act 740, then the tag detection signal is added to and OUT tag readlist at act 760. However, if the entry in the IN tag read list isidentified as old, then processing proceeds to act 745 to identifywhether the tag associated with the entry corresponds to a movement orpaired set of tag detection signals, or if the entry corresponds to anorphaned tag detection signal. If the entry corresponds to a movementpair by act 745, the entry is removed from the IN tag read list by act750. If the entry corresponds to an orphaned tag detection signal, thena corresponding orphaned tag read is added to a list of events forreporting by act 755, and the entry is removed from the OUT tag readlist by act 750. Events identified by Portal OUT process may be storedin one or more event data sets 234. Information related to these eventsmay be included in a message constructed by message generator 236 andtransmitted to a server.

FIG. 8 illustrates an exemplary embodiment for processing tag detectionsignals by Presence process 460. Method 800 may be performed, forexample, by one or more components of sensor system 226 such as signalanalyzer 228 and/or event identifier 230, although other implementationsare possible and method 800 is not limited in this respect. Stored tagdetection signals stored in tag signal data set(s) 224 may be stored inthe form of one or more tag read lists. Presence process may identifyevents associated with a tag's arrival and/or departure from a regionproximate to an antenna based on comparing the tag detection signal tostored tag detection signals associated with the one or more antennaswithin the same sensor system. The stored tag detection signals may bestored in a Presence tag read list. Processing of a tag detection signaltransmitted by an antenna configured in Presence mode includes searchinga Presence tag read list for a tag entry identifying the tagcorresponding to the tag detection signal at act 815, detecting anincoming event when the tag entry has been added recently to thePresence tag read list of acts 820 and 830, and adding the incomingevent to an event list for upload. When an incoming event is detected atact 830, the entry for the tag may be added to the Presence tag readlist at act 825.

As a background process, tag detection signals stored in Presence tagread list 860 are periodically searched to identify any old entries atact 845. The tag detection signals stored in Presence tag read list maybe reviewed at periodic time intervals configured by a user. When oldentries are present, an outgoing event is detected at act 855. The eventmay be provided to a list for upload, and the entry in the Presence tagread list may be removed. Events identified by Presence process may bestored in one or more event data sets 234. Information related to theseevents may be included in a message constructed by message generator 236and transmitted to a server.

FIG. 9 illustrates an exemplary embodiment for processing tag detectionsignals received from antennas configured to operate in Muster mode. Theprocessing tasks associated for tag detection signals transmitted byantennas operating in Muster mode include searching a Muster tag readlist for a tag entry identifying the tag corresponding to the tagdetection signal at act 915, detecting a muster event when the tag entryhas been added recently to the Muster tag read list at acts 920 and 930,and adding the muster event to an event list for upload. When a musterevent is detected at act 930, the entry for the tag is added to theMuster tag read list at act 925.

As a background process, tag detection signals stored in Muster tag readlist 960 are searched to identify any old entries at act 945. The tagdetection signals stored in the Muster tag read list may be reviewed atperiodic time intervals configured by a user. When an old entry ispresent, the entry may be removed from the Muster tag read list. Eventsidentified by Muster process may be stored in one or more event datasets 234. Information related to these events may be included in amessage constructed by message generator 236 and transmitted to aserver.

FIG. 10 illustrates an example of a suitable computing systemenvironment 1000 on which the invention may be implemented. Thecomputing system environment 1000 is only one example of a suitablecomputing environment and is not intended to suggest any limitation asto the scope of use or functionality of the invention. Neither shouldthe computing environment 1000 be interpreted as having any dependencyor requirement relating to any one or combination of componentsillustrated in the exemplary operating environment 1000.

The invention is operational with numerous other general purpose orspecial purpose computing system environments or configurations.Examples of well-known computing systems, environments, and/orconfigurations that may be suitable for use with the invention include,but are not limited to, personal computers, server computers, hand-heldor laptop devices, multiprocessor systems, microprocessor-based systems,set top boxes, programmable consumer electronics, network PCs,minicomputers, mainframe computers, distributed computing environmentsthat include any of the above systems or devices, and the like.

FIG. 10 is illustrative of the various processing capabilities that maybe used to implement different aspects of the techniques of the presentapplication. Some components may not implement all of the processingcapabilities illustrated in FIG. 10 such as a sensor unit. However,other devices such as those used to access information on the server orto provide processing hardware to the sensor unit may be implementprocessing components illustrated in FIG. 10.

The computing environment may execute computer-executable instructions,such as program modules. Generally, program modules include routines,programs, objects, components, data structures, etc. that performparticular tasks or implement particular abstract data types. Theinvention may also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a communications network. In a distributed computingenvironment, program modules may be located in both local and remotecomputer storage media including memory storage devices.

With reference to FIG. 10, an exemplary system for implementing theinvention includes a general purpose computing device in the form of acomputer 1010. Components of computer 1010 may include, but are notlimited to, a processing unit 1020, a system memory 1030, and a systembus 1021 that couples various system components including the systemmemory to the processing unit 1020. The system bus 1021 may be any ofseveral types of bus structures, including a memory bus or memorycontroller, a peripheral bus, and a local bus using any of a variety ofbus architectures. By way of example, and not limitation, sucharchitectures include Industry Standard Architecture (ISA) bus, MicroChannel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus also known as Mezzanine bus.

Computer 1010 typically includes a variety of computer readable media.Computer readable media can be any available media that can be accessedby computer 1010 and includes both volatile and nonvolatile media,removable and non-removable media. By way of example, and notlimitation, computer readable media may comprise computer storage mediaand communication media. Computer storage media includes both volatileand nonvolatile, removable and non-removable media implemented in anymethod or technology for storage of information such as computerreadable instructions, data structures, program modules or other data.Computer storage media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can accessed by computer 1010. Communication media typicallyembodies computer readable instructions, data structures, programmodules or other data in a modulated data signal such as a carrier waveor other transport mechanism and includes any information deliverymedia. The term “modulated data signal” means a signal that has one ormore of its characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared and other wireless media. Combinations of the any of the aboveshould also be included within the scope of computer readable media.

The system memory 1030 includes computer storage media in the form ofvolatile and/or nonvolatile memory such as read only memory (ROM) 1031and random access memory (RAM) 1032. A basic input/output system 1033(BIOS), containing the basic routines that help to transfer informationbetween elements within computer 1010, such as during start-up, istypically stored in ROM 1031. RAM 1032 typically contains data and/orprogram modules that are immediately accessible to and/or presentlybeing operated on by processing unit 1020. By way of example, and notlimitation, FIG. 10 illustrates operating system 1034, applicationprograms 1035, other program modules 1036, and program data 1037.

The computer 1010 may also include other removable/non-removable,volatile/nonvolatile computer storage media. By way of example only,FIG. 10 illustrates a hard disk drive 1041 that reads from or writes tonon-removable, nonvolatile magnetic media, a magnetic disk drive 1051that reads from or writes to a removable, nonvolatile magnetic disk1052, and an optical disk drive 1055 that reads from or writes to aremovable, nonvolatile optical disk 1056 such as a CD ROM or otheroptical media. Other removable/non-removable, volatile/nonvolatilecomputer storage media that can be used in the exemplary operatingenvironment include, but are not limited to, magnetic tape cassettes,flash memory cards, digital versatile disks, digital video tape, solidstate RAM, solid state ROM, and the like. The hard disk drive 1041 istypically connected to the system bus 1021 through a non-removablememory interface, such as interface 1040, and magnetic disk drive 1051and optical disk drive 1055 are typically connected to the system bus1021 by a removable memory interface, such as interface 1050.

The drives and their associated computer storage media discussed aboveand illustrated in FIG. 10, provide storage of computer readableinstructions, data structures, program modules and other data for thecomputer 1010. In FIG. 10, for example, hard disk drive 1041 isillustrated as storing operating system 1044, application programs 1045,other program modules 1046, and program data 1047. Note that thesecomponents can either be the same as or different from operating system1034, application programs 1035, other program modules 1036, and programdata 1037. Operating system 1044, application programs 1045, otherprogram modules 1046, and program data 1047 are given different numbershere to illustrate that, at a minimum, they are different copies. A usermay enter commands and information into the computer 1010 through inputdevices such as a keyboard 1062 and pointing device 1061, commonlyreferred to as a mouse, trackball or touch pad. Other input devices (notshown) may include a microphone, joystick, game pad, satellite dish,scanner, or the like. These and other input devices are often connectedto the processing unit 1020 through a user input interface 1060 that iscoupled to the system bus, but may be connected by other interface andbus structures, such as a parallel port, game port or a universal serialbus (USB). A monitor 1091 or other type of display device is alsoconnected to the system bus 1021 via an interface, such as a videointerface 1090. In addition to the monitor, computers may also includeother peripheral output devices such as speakers 1097 and printer 1096,which may be connected through an output peripheral interface 1095.

The computer 1010 may operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computer1080. The remote computer 1080 may be a personal computer, a server, arouter, a network PC, a peer device or other common network node, andtypically includes many or all of the elements described above relativeto the computer 1010, although only a memory storage device 1081 hasbeen illustrated in FIG. 10. The logical connections depicted in FIG. 10include a local area network (LAN) 1071 and a wide area network (WAN)1073, but may also include other networks. Such networking environmentsare commonplace in offices, enterprise-wide computer networks, intranetsand the Internet.

When used in a LAN networking environment, the computer 1010 isconnected to the LAN 1071 through a network interface or adapter 1070.When used in a WAN networking environment, the computer 1010 typicallyincludes a modem 1072 or other means for establishing communicationsover the WAN 1073, such as the Internet. The modem 1072, which may beinternal or external, may be connected to the system bus 1021 via theuser input interface 1060, or other appropriate mechanism. In anetworked environment, program modules depicted relative to the computer1010, or portions thereof, may be stored in the remote memory storagedevice. By way of example, and not limitation, FIG. 10 illustratesremote application programs 1085 as residing on memory device 1081. Itwill be appreciated that the network connections shown are exemplary andother means of establishing a communications link between the computersmay be used.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” “having,” “containing”, “involving”, andvariations thereof, is meant to encompass the items listed thereafterand additional items. Use of ordinal terms such as “first,” “second,”“third,” etc., in the claims to modify a claim element does not byitself connote any priority, precedence, or order of one claim elementover another or the temporal order in which acts of a method areperformed. Ordinal terms are used merely as labels to distinguish oneclaim element having a certain name from another element having a samename (but for use of the ordinal term), to distinguish the claimelements from each other.

Having described several embodiments of the invention in detail, variousmodifications and improvements will readily occur to those skilled inthe art. Such modifications and improvements are intended to be withinthe spirit and scope of the invention. Accordingly, the foregoingdescription is by way of example only, and is not intended as limiting.The invention is limited only as defined by the following claims and theequivalents thereto.

What is claimed is:
 1. A system comprising: a plurality of antennasdeployed in a location, wherein each antenna of the plurality ofantennas is configured to receive a signal indicative of a tag proximateto the antenna; a memory; a processor configured to: process tagdetection signals that are based on the received signals, wherein theprocessing comprises: selectively storing tag detection signals in thememory; and identifying an event related to presence of a tag at thelocation based on a plurality of tag detection signals, the plurality oftag detection signals comprising at least one stored tag detectionsignal, wherein the event is representative of a combination of at leasta portion of the plurality of tag detection signals, wherein the portioncomprises tag detection signals associated with different antennas ofthe plurality of antennas; and a transmitter configured to transmit amessage indicating the event over a wide area network to a server. 2.The system of claim 1, wherein identifying an event comprisesidentifying that a tag detection signal of the plurality of tagdetection signals includes tag identification information that matchestag identification information of the at least one stored tag detectionsignal.
 3. The system of claim 2, wherein the tag detection signal ofthe plurality of tag detection signals is based on signals received by afirst antenna of the plurality of antennas and the at least one storedtag detection signal is based on signals received by a second antenna ofthe plurality of antennas.
 4. The system of claim 1, wherein: theprocessor is further configured to store time information associatedwith the at least one stored tag detection signal, and identifying anevent comprises comparing the time information associated with the atleast one stored tag detection signal to time information associatedwith at least one other tag detection signal of the plurality of tagdetection signals.
 5. The system of claim 4, wherein an event isidentified by comparing a difference between the time informationassociated with the at least one other tag detection signal and the timeinformation associated with the at least one stored tag detection signalto a time interval.
 6. The system of claim 4, wherein an event isidentified when a difference between the time information associatedwith the tag detection signal of the plurality of tag detection signalsand the time information associated with the at least one stored tagdetection signal is greater than a time interval, and the tag detectionsignal of the plurality of tag detection signals includes tagidentification information that is distinct from the tag identificationinformation of the at least one stored tag detection signal.
 7. Thesystem of claim 4, wherein an event is identified by an absence of atleast one tag detection signal corresponding to the tag for an amount oftime exceeding a time interval.
 8. The system of claim 1, wherein the atleast one stored tag detection signal is modified to reflect theidentified event.
 9. The system of claim 1, wherein the at least onestored tag detection signal is deleted from the memory when a differencebetween time information associated with the at least one stored tagdetection signal and a current time is greater than a predetermined timeinterval.
 10. The system of claim 1, wherein the transmitter isconfigured to transmit the message via at least one data buffer, and theat least one data buffer is configured to store at least a portion ofthe message when the transmitter is unable to transmit the message. 11.The system of claim 1, wherein the transmitter is configured to transmitat least a portion of the message over the wide area network when thesystem is in communication with the server and the at least one databuffer is configured to store at least a portion of the message whentransmission of the message is interrupted.
 12. A system comprising: awide area network receiver configured to receive, from a sensor unithaving a plurality of antennas, a message reporting at least one eventidentified by the sensor unit processing signals received from a tagproximate to an antenna of the plurality of antennas and at least onefeature of the signals including signal strength; a processor configuredto: process the message, wherein the processing comprises: analyzing theat least one event and signal strength of the signals to evaluateadjustment of a power setting used to operate the at least one antennaof the plurality of antennas; and updating the power setting whenanalysis of the at least one event and the signal strength indicatesadjusting the power setting; and a wide area network transmitterconfigured to transmit the updated power setting to the sensor unit. 13.The system of claim 12, wherein processing the message further comprisesanalyzing the at least one event to identify a portion of the at leastone event that consolidates a number of occurrences for an event type.14. The system of claim 12, wherein processing the message furthercomprises analyzing the at least one event and the at least one featureto identify information indicative of a status of the sensor unit, andthe processor is further configured to present a status messageindicating the status to a user.
 15. The system of claim 12, wherein theupdated power setting is used to operate the at least one antenna inresponse to the sensor unit receiving the updated power setting.
 16. Thesystem of claim 12, wherein processing the message further comprisespresenting information related to the message to a user, wherein theinformation presented to the user indicates a status of the sensor unit.17. At least one non-transitory computer-readable medium storingcomputer-executable instructions that, when executed, perform a methodcomprising: receiving, from a plurality of antennas deployed in alocation and configured to detect different event types, signalsindicating a tag proximate to an antenna of the plurality of antennas;processing, by a reader unit in communication with the plurality ofantennas, tag detection signals that are based on the received signals,wherein the processing comprises: selectively storing tag detectionsignals; and identifying events related to presence of a tag at thelocation based on a plurality of tag detection signals and informationidentifying an event type associated with at least one antenna of theplurality of antennas corresponding to the plurality of tag detectionsignals, the plurality of tag detection signals comprising at least onestored tag detection signal, and wherein the events include a pluralityof event types and each of the events represent a combination ofmultiple tag detection signals of the plurality of tag detectionsignals; and transmitting a message indicating the events from thereader unit over a wide area network to a server.
 18. The at least onenon-transitory computer-readable medium of claim 17, wherein thereceived signals indicate at least one configuration parameter of theantenna, and identifying events is based on the at least oneconfiguration parameter.
 19. The at least one non-transitorycomputer-readable medium of claim 17, wherein the plurality of eventtypes includes an event type corresponding to arrival of the tag to aregion proximate to an antenna of the plurality of antennas at thelocation.
 20. The at least one non-transitory computer-readable mediumof claim 17, wherein the plurality of event types includes an event typecorresponding to departure of the tag from a region proximate to anantenna of the plurality of antennas at the location.
 21. The at leastone non-transitory computer-readable medium of claim 17, wherein theplurality of event types includes an event type corresponding tomovement of a user associated with the tag from a first region proximateto a first antenna at the location to a second region proximate to asecond antenna at the location.